

MUSCLES CONNECTED WITH THE SHOULDER-JOINT. 623 



Crocodile, underneath the epicoraco-humeral and the deltoid, and supplied by the sam. 

 nerve as the former of these muscles. It lakes origiB from the triangular surface (jt, 

 fig. 1) intercepted between the deltoid ridge, d, and the scapulo-coracoid figure, and 

 it is inserted just where the pectoral ridge sinks into the articular head of the humerus, 

 proximally to the tendon of the teres minor. The suprascapular muscle is not ordinarily 

 differentiated in reptiles into an infra- and supraspinal us. But in a (Jecko, Platydae- 

 tylus, sp. ?, I have observed it to take origin from the coracoid, as well as from the 

 scapular region of the shoulder- girdle ; and by doing this, it has broti lit it sell" by origin, 

 as it is often by innervation, into close eorrespondenco with the comco-hmch des 

 muscles, and, serially, with the iliacus of reptiles. 



The muscle seen in fig. 4, intercepted between the tendon of the biraps and that of the 

 pectoralis secuudns is called "deltoides internus" by Meckel ; it is, however, obviously 

 homologous with an upper segment of the coraco-brackiali*. as sc n in fi" 3 from the 



Crocodile, and with the "short coracobrachial is" or "rotator humeri" of Wood (Cam- 

 bridge Journal of Anatomy and Physiology, ftov. 1800, p. 49). 



The muscle described by Mr. Mivart in the Iguana tuherculata, under the name of 

 "gracilis," and stated by him to "represent possibly the gracilis of mammals," seems t<. 

 me to be a serial homologue, which I have not met with elsewhere, of the pedum Us 

 major. It arises from "the ischiatic symphysis" (where, in the s mrians, an o^ ilic 

 nodule, the os cloaca?, may not rarely be found placed mesially, as though representing 

 a sternum), and "from the long tendinous arch which passes from the front of the 

 acetabulum, round behind the pubic spine, back to the symphysis just mentioned." This 

 latter origin seems to me to correspond with the interclavicular and clavicular origin ol 

 the pectoral, as seen in some of the Sauropsida, and, as far as regards the clavicle, in 

 mammals. Its insertion into the peroneal side of the head of the tibia seems to me to 

 be paralleled by the insertion of the the pedo-antebrachial of certain mammaK e. g. the 

 Cat (see Straus-Diirckheim, vol. ii. p. 352, pi. vii. figs. 13, 15). Mr. Mivart, by lettering 

 his tibial adductor S, may be understood, perhaps, to mean that he considers this muscle 

 homologous with the sartorius of anthropotomy ; and in this identification I should 

 coincide. But the gracilis, which he seems to think may perhaps be represented by the 

 muscle I suppose to be homologous with the pectoralis major, I think must be repre- 

 sented by a head which the tibial adductor in the Iguana tuherculata examined by me 

 received from the symphysis of the ischia. 



Mr. Mivart's ilio-peroneal seems to me to have its serial homologue in the muscle 

 which, in many mammals, passes from the posterior vertebral angle of the scapula down 

 to the olecranon, and which seems to be a divarication of the more commonly found 

 " dorso-epitrochlien." As this muscle is clearly one of the series made up of the biceps, 

 semimembranosus, and semitendinosus, which, like itself, take origin, in Crocodilidae, from 

 the ilium, it may be suggested that in the muscle just mentioned, as found in certain 

 mammals, among which I may specify the Marten {Mustela martes), may be contained 

 the homologues of the biceps, semimembranosus, and semitendinosus, as well as the ilio- 

 peroneal of the lower limb. This great increase of the number of the muscles of the 

 lower, as compared with that of their homologues in their upper limb, is illustrated also 



VOL. XXVI. 



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